Vulnerabilities > CVE-2018-5244 - Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerability in XEN
Attack vector
LOCAL Attack complexity
LOW Privileges required
LOW Confidentiality impact
NONE Integrity impact
NONE Availability impact
HIGH Summary
In Xen 4.10, new infrastructure was introduced as part of an overhaul to how MSR emulation happens for guests. Unfortunately, one tracking structure isn't freed when a vcpu is destroyed. This allows guest OS administrators to cause a denial of service (host OS memory consumption) by rebooting many times.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Buffer Overflow via Environment Variables This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
- Overflow Buffers Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an attacker. As a consequence, an attacker is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the attackers' choice.
- Client-side Injection-induced Buffer Overflow This type of attack exploits a buffer overflow vulnerability in targeted client software through injection of malicious content from a custom-built hostile service.
- Filter Failure through Buffer Overflow In this attack, the idea is to cause an active filter to fail by causing an oversized transaction. An attacker may try to feed overly long input strings to the program in an attempt to overwhelm the filter (by causing a buffer overflow) and hoping that the filter does not fail securely (i.e. the user input is let into the system unfiltered).
- MIME Conversion An attacker exploits a weakness in the MIME conversion routine to cause a buffer overflow and gain control over the mail server machine. The MIME system is designed to allow various different information formats to be interpreted and sent via e-mail. Attack points exist when data are converted to MIME compatible format and back.
Nessus
NASL family Misc. NASL id XEN_SERVER_XSA-253.NASL description According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a guest-to-host denial of service vulnerability. Note that Nessus has checked the changeset versions based on the xen.git change log. Nessus did not check guest hardware configurations or if patches were applied manually to the source code before a recompile and reinstall. last seen 2020-06-01 modified 2020-06-02 plugin id 105775 published 2018-01-12 reporter This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/105775 title Xen vcpu Destruction Handling Memory Exhaustion Guest-to-Host DoS (XSA-253) code # # (C) Tenable Network Security, Inc. # include("compat.inc"); if (description) { script_id(105775); script_version("1.5"); script_cvs_date("Date: 2019/11/08"); script_cve_id("CVE-2018-5244"); script_bugtraq_id(102433); script_xref(name:"IAVB", value:"2018-B-0013"); script_name(english:"Xen vcpu Destruction Handling Memory Exhaustion Guest-to-Host DoS (XSA-253)"); script_summary(english:"Checks 'xl info' output for the Xen hypervisor version."); script_set_attribute(attribute:"synopsis", value: "The remote Xen hypervisor installation is missing a security update."); script_set_attribute(attribute:"description", value: "According to its self-reported version number, the Xen hypervisor installed on the remote host is affected by a guest-to-host denial of service vulnerability. Note that Nessus has checked the changeset versions based on the xen.git change log. Nessus did not check guest hardware configurations or if patches were applied manually to the source code before a recompile and reinstall."); script_set_attribute(attribute:"see_also", value:"http://xenbits.xen.org/xsa/advisory-253.html"); script_set_attribute(attribute:"see_also", value:"https://xenbits.xen.org/gitweb/?p=xen.git;a=summary"); script_set_attribute(attribute:"solution", value: "Apply the appropriate patch according to the vendor advisory."); script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:N/I:N/A:C"); script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C"); script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H"); script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C"); script_set_attribute(attribute:"cvss_score_source", value:"CVE-2018-5244"); script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available"); script_set_attribute(attribute:"exploit_available", value:"false"); script_set_attribute(attribute:"vuln_publication_date", value:"2018/01/04"); script_set_attribute(attribute:"patch_publication_date", value:"2018/01/04"); script_set_attribute(attribute:"plugin_publication_date", value:"2018/01/12"); script_set_attribute(attribute:"potential_vulnerability", value:"true"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"cpe:/o:xen:xen"); script_set_attribute(attribute:"stig_severity", value:"I"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_family(english:"Misc."); script_copyright(english:"This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof."); script_dependencies("xen_server_detect.nbin"); script_require_keys("installed_sw/Xen Hypervisor", "Settings/ParanoidReport"); exit(0); } include("audit.inc"); include("global_settings.inc"); include("install_func.inc"); include("misc_func.inc"); app_name = "Xen Hypervisor"; install = get_single_install(app_name:app_name); if (report_paranoia < 2) audit(AUDIT_PARANOID); version = install['version']; display_version = install['display_version']; path = install['path']; managed_status = install['Managed status']; changeset = install['Changeset']; if (!empty_or_null(changeset)) display_version += " (changeset " + changeset + ")"; # Installations that are vendor-managed are handled by OS-specific local package checks if (managed_status == "managed") audit(AUDIT_INST_PATH_NOT_VULN, app_name, display_version, path); fixes['4.10']['fixed_ver'] = '4.10.1'; fixes['4.10']['fixed_ver_display'] = '4.10.1-pre (changeset a87ec48)'; fixes['4.10']['affected_ver_regex'] = '^4\\.10\\.'; fixes['4.10']['affected_changesets'] = make_list("9dc5eda", "135b67e", "682a9d8", "19dcd8e", "e5364c3", "e2dc7b5", "c8f4f45", "4150501", "ab7be6c", "f3fb667"); fix = NULL; foreach ver_branch (keys(fixes)) { if (version =~ fixes[ver_branch]['affected_ver_regex']) { ret = ver_compare(ver:version, fix:fixes[ver_branch]['fixed_ver']); if (ret < 0) fix = fixes[ver_branch]['fixed_ver_display']; else if (ret == 0) { if (empty_or_null(changeset)) fix = fixes[ver_branch]['fixed_ver_display']; else foreach affected_changeset (fixes[ver_branch]['affected_changesets']) if (changeset == affected_changeset) fix = fixes[ver_branch]['fixed_ver_display']; } } } if (empty_or_null(fix)) audit(AUDIT_INST_PATH_NOT_VULN, app_name, display_version, path); items = make_array( "Installed version", display_version, "Fixed version", fix, "Path", path ); order = make_list("Path", "Installed version", "Fixed version"); report = report_items_str(report_items:items, ordered_fields:order) + '\n'; security_report_v4(port:0, extra:report, severity:SECURITY_WARNING);
NASL family Gentoo Local Security Checks NASL id GENTOO_GLSA-201810-06.NASL description The remote host is affected by the vulnerability described in GLSA-201810-06 (Xen: Multiple vulnerabilities) Multiple vulnerabilities have been discovered in Xen. Please review the referenced CVE identifiers for details. Impact : A local attacker could cause a Denial of Service condition or disclose sensitive information. Workaround : There is no known workaround at this time. last seen 2020-06-01 modified 2020-06-02 plugin id 118506 published 2018-10-31 reporter This script is Copyright (C) 2018-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/118506 title GLSA-201810-06 : Xen: Multiple vulnerabilities (Foreshadow) (Meltdown) (Spectre)